Most feeding problems on a first grow come from too much, not too little. Nutrient bottles are often written for experienced growers pushing plants hard, and following them at full strength from day one is one of the fastest ways to burn a young plant.
This guide gives you a feeding framework you can apply to any nutrient brand: what the plant needs at each stage, how to start low and adjust, and how pH decides whether your plant can use any of it. You’ll also find a printable chart you can fill in with your own nutrient line.
The short version:
- Seedlings: little or nothing. Pre-fertilized soil often covers the first weeks.
- Vegetative: nitrogen-forward “grow” nutrients, starting at a fraction of the label dose.
- Early flower: transition to “bloom” nutrients (less nitrogen, more phosphorus and potassium).
- Late flower: many growers taper feeding as harvest approaches.
- Always: check pH, and let the plant (not the bottle) tell you when to increase.
What Cannabis Actually Needs
The big three: N-P-K
Every nutrient label lists three numbers: nitrogen (N), phosphorus (P) and potassium (K).
- Nitrogen fuels leafy green growth. Plants use the most during vegetative growth.
- Phosphorus supports roots and flower development.
- Potassium supports overall plant function, including water regulation and flower development.
“Grow” formulas lean on nitrogen; “bloom” formulas lean on phosphorus and potassium.
Secondary nutrients and micronutrients
Calcium, magnesium and sulfur are needed in moderate amounts. Calcium and magnesium shortages are especially common in coco coir and with very soft or filtered water, which is why many growers add a “Cal-Mag” supplement there.
Micronutrients (iron, manganese, zinc, boron, copper, molybdenum and others) are needed in tiny amounts. Complete nutrient lines include them; you rarely need to add them separately.
Water, light and roots come first
Nutrients can’t fix a plant that’s overwatered, under-lit or root-bound. If the environment is off, extra feeding usually makes things worse.
The Golden Rule: Start Low, Go Slow
Here’s the method we use with any brand:
- Find the manufacturer’s feeding chart for your nutrient line and medium.
- Start at a fraction of the recommended dose. Many growers begin around a quarter to half strength. That’s a common cautious habit, not a measured rule.
- Watch the plant for several days. Look at new growth and the lower leaves.
- Adjust in small steps:
- Lower leaves fading to pale yellow from the bottom up while the rest looks healthy → plant may be hungry; increase a little.
- Leaf tips turning brown and crispy, or leaves dark and clawing down → too much; back off.
- Healthy deep-green leaves with no tip burn → you’re in the zone. Don’t change anything.
That’s the whole system. The chart below just tells you which nutrients to emphasize when.
Feeding by Growth Stage
Stage 1: Germination and seedlings
- Feeding: usually none. The seed carries its own early food, and many potting mixes include a starter charge of nutrients.
- In coco or hydro: seedlings need a very mild solution because the medium holds little or no food. Follow the manufacturer’s seedling dose, then go lighter.
- pH: start checking now so it’s a habit.
Stage 2: Vegetative growth
- Focus: nitrogen-forward grow nutrients.
- Soil: begin feeding when the plant shows it’s using up what’s in the mix (lower leaves lightening). Some growers alternate feed and plain water.
- Coco: feed with most waterings. Add Cal-Mag if your line recommends it.
- Hydro: follow the line’s chart for reservoir strength and change the reservoir on the schedule the manufacturer recommends.
Stage 3: Transition / early flower
- Autoflowers move into flower on their own; photoperiod plants after the switch to 12/12.
- Focus: gradually shift from grow nutrients to bloom nutrients over about a week or two, rather than all at once.
- The plant is still stretching and building leaves, so don’t cut nitrogen to zero.
Stage 4: Mid to late flower
- Focus: bloom nutrients (more phosphorus and potassium). Some lines add a “booster” for this stage. Use boosters cautiously; they’re an easy way to overfeed.
- It’s normal for older fan leaves to yellow late in flower as the plant draws nutrients for buds.
Stage 5: The final weeks before harvest
- Many growers reduce or stop feeding in the last week or two and give plain pH’d water, often called a “flush.” Growers debate how much difference it makes; it’s common practice, especially in coco and hydro.
The Hollywood Feeding Chart (Fill-In Template)
This is a framework, not a dosage. Fill in the doses from your nutrient brand’s chart, then apply the start-low rule.
| Week (from sprout) | Stage (typical autoflower; your strain may differ) | Nutrient focus | Strength vs label | Notes |
|---|---|---|---|---|
| 1–2 | Seedling | None (soil) / very mild (coco, hydro) | 0–25% | Water lightly in a ring around the stem |
| 3–4 | Early veg | Grow | 25–50% | Increase only if lower leaves fade |
| 4–5 | Late veg / pre-flower | Grow → begin transition | 50–75% | Start LST now if you’re training |
| 5–7 | Early flower / stretch | Grow + bloom blend | 50–75% | Watch for Cal-Mag needs in coco |
| 7–9 | Mid flower | Bloom | 50–100% | Back off at first sign of tip burn |
| 9+ | Late flower | Bloom, tapering | Reduce | Check trichomes for harvest timing |
| Final 1–2 weeks | Pre-harvest | Plain pH’d water (optional) | 0% | Lower leaves fading is normal |
Photoperiod plants: veg lasts as long as you choose. Use the “veg” rows for the whole veg period, then follow the flower rows from the day you switch to 12/12.
Strength percentages are illustrative starting points for cautious beginners, not a manufacturer recommendation. Always read your product label.
Free from our partner ILGM. Affiliate links: we may earn a commission at no extra cost to you.
Recommended seeds to start with
For a first grow, most people have the easiest time with feminized autoflowers: no light-schedule switch, compact plants and a shorter run. Two good places to start browsing at ILGM:
- ILGM autoflower seeds: ILGM's full autoflower range.
- ILGM beginner seeds: the strains ILGM groups as beginner-friendly.
Affiliate links: we may earn a commission at no extra cost to you. Check your state's rules before you order seeds: Grow Laws by State.
pH: The Setting That Makes or Breaks Feeding
Plants can only absorb nutrients within a certain pH range. Outside it, nutrients get “locked out,” and the plant shows deficiency symptoms even though the food is right there.
Commonly recommended ranges:
| Medium | Typical target pH for water/nutrient solution |
|---|---|
| Soil | about 6.0–7.0 |
| Coco coir | about 5.5–6.5 |
| Hydroponics | about 5.5–6.5 |
How to manage it: 1. Mix nutrients into water first, then measure pH (nutrients shift pH). 2. Adjust with pH up/down solutions a few drops at a time, stirring and re-measuring. 3. Calibrate digital pH pens on the schedule the manufacturer recommends. An uncalibrated meter is worse than none.
Gear: a digital pH pen is the one meter every grower needs. VIVOSUN is one brand that sells them; whichever you buy, get calibration solution too.
EC/PPM: Measuring Feed Strength
An EC (electrical conductivity) or PPM meter measures how much dissolved fertilizer is in your water. It’s optional in soil and very useful in coco and hydro.
- Measure your plain tap water first so you know your starting point.
- Measure your nutrient mix and compare it to the range your nutrient line recommends.
- In coco and hydro, some growers also measure runoff to see whether salts are building up in the medium.
Note: PPM meters use different conversion scales, so a “PPM” number from one meter may not match another. EC is the more universal unit.
Soil vs Coco vs Hydro: How Feeding Differs
| Soil | Coco coir | Hydro | |
|---|---|---|---|
| Built-in nutrients | Often some (pre-fertilized mixes) | Essentially none | None |
| How often to feed | Every other watering or less, as needed | Most waterings | Constantly (reservoir) |
| Forgiveness | Highest | Medium | Lowest |
| Cal-Mag supplement | Sometimes | Often | Depends on water and line |
| Best for | First grows | Second grows / faster growth | Experienced growers |
Organic “just add water” soils are another option: a rich living soil that feeds the plant through microbial activity, with little or no bottled nutrients. Lower maintenance, less control.
Reading Your Plant: Feeding Problems at a Glance
| What you see | Likely cause | First thing to try |
|---|---|---|
| Brown, crispy leaf tips | Overfeeding (“nutrient burn”) | Reduce strength; water with plain pH’d water |
| Dark green leaves clawing down | Too much nitrogen | Reduce grow nutrient |
| Lower leaves yellowing from the bottom up (in veg) | Nitrogen deficiency | Increase feed slightly |
| Rusty spots, yellowing between veins | Possible calcium/magnesium issue or pH lockout | Check pH first, then consider Cal-Mag |
| Symptoms that don’t respond to feeding changes | pH out of range | Calibrate meter, re-check pH |
| Droopy, heavy leaves and wet pot | Overwatering (not a nutrient problem) | Let the pot dry out |
More help in our Troubleshooting hub.
Choosing Nutrients
- Beginner pick: a simple two- or three-part line with a clear chart for your medium. Fewer bottles, fewer mistakes.
- Bundles: some seed banks and kit sellers offer nutrient sets matched to their grow approach. ILGM, for example, sells its own cannabis nutrients. Check current products and prices on its site.
- Avoid: stacking several boosters and additives on a first grow. Master the base line first.
Frequently Asked Questions
When should I start feeding cannabis seedlings?
In most pre-fertilized soils, not for the first couple of weeks. Start when lower leaves begin to lighten. In coco or hydro, give a very mild solution from early on because the medium contains no food.
How often should I feed my plants?
In soil, many growers feed every other watering or less. In coco, most waterings. In hydro, nutrients are always in the reservoir. Let the plant’s response guide you.
Should I use the full dose on the bottle?
Not at first. Start below the label dose and increase in small steps only if the plant shows it’s hungry.
Do autoflowers need less food than photoperiods?
Autos are generally smaller and many growers feed them more lightly. Follow the start-low approach and watch the plant.
What pH should my water be for cannabis?
Commonly cited targets are about 6.0–7.0 in soil and about 5.5–6.5 in coco and hydro. Measure after mixing nutrients.
Do I need to flush before harvest?
It’s a widespread practice, especially in coco and hydro, but growers disagree about how much it matters. Feeding plain pH’d water in the final week or two is a low-risk option.
Can I use a vegetable fertilizer?
Many general-purpose fertilizers can work, but they aren’t tailored to the shift from veg to flower. A cannabis-oriented two- or three-part line makes stage changes easier.
Disclaimer: For adults 21+ and educational use only. Always follow product labels and safety directions. Grow only where legal.